Fuel supplying apparatuses vaporize liquefied fuel into gas fuel and supply such gas fuel to gas engines. These apparatuses have problems that tar produced after the vaporization of the liquefied fuel remains within the apparatuses. The remaining tar can deteriorate rubber components such as diaphragms, clog up jet ports of the apparatuses, or hinder flow control valve from closely contacting valve seats.
JP-U-64-19052 and JP-U-64-21252 disclose fuel supplying apparatuses for gas engines, which are designed to address those problems. The disclosed apparatuses include heaters for heating fuel passageways which interconnect vaporizers and mixers.
The apparatus disclosed in JP-U-64-19052 includes a main fuel passageway which interconnects a secondary chamber of a vaporizer and a venturi of a mixer, and a low-speed fuel passageway which interconnects a primary chamber of the vaporizer and a portion of the mixer disposed below the venturi. Attached to these passageways are first and second heaters that are made of nichrome wires.
The apparatus disclosed in JP-U-64-21252 includes a heater attached to both a main fuel passageway and a low-speed fuel passageway and configured to guide engine-cooling water through the heater.
Some small-sized general-purpose engine does not carry a battery or a generator, for decreased cost and weight, etc of the engine. It is difficult for such small-sized general purpose engines to carry the electric heaters as disclosed in JP-U-64-19052 or the heater utilizing the engine-cooling water as disclosed in JP-U-64-21252 because these general-purpose engines are air-cooled engines.
Other than the above heaters, heating means may include ones that use engine-cooling air or exhaust heat from mufflers, but such heating means have temperatures that are difficult to control. For the small-sized general-purpose engines, therefore, there is a need for a simple structure designed to efficiently discharge tar out of fuel passageways without utilizing the heaters.